A six-year longitudinal followup study is proposed to evaluate age-related slowing in decision-making and memory processes. The instruments would be a group of psychological measures that were originally administered in 1971-1973. The subjects would be male volunteers from an interdisciplinary longitudinal study of normal aging: the Normative Aging Study, conducted by the Veterans Administration Outpatient Clinic. The research is designed to accomplish four objectives: 1) to evaluate specific hypotheses about the locus of age-related differences in perceptual-motor and decision-making components of response latencies; 2) to relate changes in the cognitive processes to various indices of current and past health status, life style and personality characteristics available on the same individual; 3) to assess possible influences of practice effects of the experimental tasks on the degree of observed age-related difference; and 4) to evaluate similarities and differences in cross-sectional and in longitudinal measurements of performance.